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Java file path f.exists() always returns false

I'm trying to create a basic Java program that allows the user create files and folders.
I want all this to happen in a folder inside my project (image attached) so I've got some doubts...
This would be my proyect tree
Is the folder "Test" correctly placed? if not how do i access to it? As you see, it's inside com.company, should I move it to src?
When I try to check if exists, it says false.
This is my code:
public class Main {
Scanner input = new Scanner(System.in);
public static void main(String[] args) {
Main main = new Main();
main.init();
}
public void init(){
File f = new File("Test"); //Here i've tried "com"+File.separator+"company"+File.separator+"Test"
System.out.println(f.exists()); //output is false here
}
}
f.getParent() says null.
But when I try: System.out.println(f.getAbsolutePath()); it shows correctly the whole path.
The point of using relative path is because i'd like this code to work on ANY computer.
Thanks in advice, hope someone could help me a bit.

If you use relative pathnames in Java, they will be resolved relative to the running application's working directory. So you need to know what the working directory is going to be.
When you are launching an application in an IDE, the working directory depends on the IDE and the launcher configs. But it is typically the file system directory that corresponds to the top of the project.
Another thing to note is that the src folder you see is special. The entries in it are typically not files and directories. The are typically Java packages and classes. So in the file system, "src" > "com.company" > "Main" is actually represented as a file with the path "src/com/company/Main.java".
This means that it is kind of wrong to put arbitrary folders and files into the "src" folder. It will work ... but it is conceptually wrong. Data files don't belong in the source tree, and certainly not data files written by your application. (And when you start using a source control system, you will find that writing data files into your source tree is going to give you a headache. I won't go into details ... but I am pretty sure that you would regret it.)
The other thing that is conceptually wrong about what you are doing is that Java programs are normally written to be free standing things. The user of your program should not need to download and install Intellij or some other IDE and load your project into it. They will want to just run it from a JAR file. In that world, the project directory and the "src" folder won't exist, and hardwiring relative paths like "src/Test" will be problematic.
So lets ignore that for now and look at what your code is currently doing
Is the folder "Test" correctly placed? if not how do i access to it? As you see, it's inside com.company, should I move it to src?
According to the image, the Test folder (actually package) >>is<< in the src Folder.
When I try to check if exists, it says false.
Your code is using the wrong path. With the "Test" folder places where you have it (according to the picture!), the relative path should be "src/Test", not "Test" or "com/company/Test".
Note that Windows accepts either "/" or "\" will work as a file separator, even though "\" is what is used conventionally.
f.getParent() says null.
That is correct. The relative path "Test" does not have a parent part. It is a simple file / directory name.
Think of it this way. Until a File with a relative path is resolved, it is not determined what directory it is relative to.
But when I try: System.out.println(f.getAbsolutePath()); it shows correctly the whole path.
Again, correct.
When you call f.getAbsolutePath() on a relative File, the runtime system prepends the path of the application's working directory, and then gives you the result.
The point of using relative path is because I'd like this code to work on ANY computer.
That relative path will NOT work on ANY computer. You are using a path that is within your project's src tree, and your project typically won't exist on an end-user's computer. (See above.)
So what should you do?
There is no single correct answer.
You could put the file / directory into the user's current / working directory.
You could put the file / directory into the user's home directory, or a hidden subdirectory in the home directory. (This is a common approach on Linux.)
You could make the pathname for the directory a command line argument
You could get the pathname from an environment variable
You could get the pathname from an application specific config file.
The best answer will depend on the context.

According to your picture the path is wrong, you should check inside the src directory:
File f = new File("src/Test");
System.out.println(f.exists());

Relative path using Level hierarchy(../../)

I want to use the relative path in xml files in our project. I have the files in the following location.
D:/SDC-Builds/SRDM2.3.0/SRDM/Svr/IdP/IdPserver/conf/attribute-r.xml
I have other xml file which needs to ref the above location, I use the following relative path to be independent of machines and folder names.
In D:/SDC-Builds/SRDM2.3.0/SRDM/Svr/IdP/IdPserver/others/service.xml, i am using the code like below
service.xml
<srv:ConfigurationResource="../../../../../../IdP/IdPserver/conf/attribute-r.xml">
</srv>
Please tell me am i using proper convention to refer the attribute-r.xml ?

If your Project Root Directory is SRDM, then you need to get back from your executable path.
Say you have your exe file at SRDM/Svr/bin/EXECUTABLE.exe then,
you need to mention in xml as
<srv:ConfigurationResource="../IdP/IdPserver/conf/attribute-r.xml"></srv>
ie. Current working directory is SRDM/Svr/bin/ and from that you need to get back up to common junction[Svr] in your case.

Correct Place to put .p12 File in a Java Web Application?

I am trying to access a .p12 in my java web application. Where is the correct place to put the file and what line of code do I need to access the file as an InputStream. I am using the line below, but the class is not finding the file.
I currently have the file in WEB-INF/classes/theFile and am using:
InputStream inputStream = this.getClass().getClassLoader().getResourceAsStream("nameOfTheFile.p12");
to access the file
Any help would be appreciated. Thanks!

This answer works for any file, not just ".p12" files.
Put a "/" in front of the name of your file (so, "/nameOfTheFile.p12" in your case) to specify an absolute path that will be resolved by using the classpath (which includes the WEB-INF/classes directory).
When you use a path without a leading "/", it is a relative path (vs. absolute path), specifically relative to the working directory of Tomcat or whatever container you are using. Even if you can find your resource using a relative path, you should not; doing so will end up hard coding deployment/packaging details within your application.

Saving a file in Windows

I have a folder called WalnutiQ. Inside this folder is is a file at WalnutiQ/train/model/MARK_II/Save.java
Save.java
JsonFileInputOutput.saveObjectToTextFile(myObjectJson,
"Digits.txt");
which works! However, the file Digits.txt is unfortunately saved in WalnutiQ/Digits.txt
How do I save the file Digits.txt at WalnutiQ/train/model/MARK_II/Digits.txt???
I am programming in java in eclipse in windows. I have tried
JsonFileInputOutput.saveObjectToTextFile(myObjectJson,
"/train/model/MARK_II/Digits.txt");
JsonFileInputOutput.saveObjectToTextFile(myObjectJson,
"\\train\\model\\MARK_II\\Digits.txt");
but neither work.

judging from the result you are getting your current directory is pointed at WalnutIQ. You might try using .\train\model\MARK_II\Digits.txt. Windows treats the . (period) as a token for "current directory". Your other attempt would have tried to find the train directory in the root of C because the \ (backslash) is a token for the root (c:). It likely fails because that folder does not exist - unless it created it... might go look :) I don't use Json in eclipse which is why I'm not answer your question with code.

Have you considered using the full absolute file path to the text file, rather than the relative one you are currently using? This may not be practical, depending on how you plan on using your program, but it might be worth a shot.

Depending on how the library saves files (I imagine it's using File behind the scenes), you should be able to supply an absolute path to the location you want it to save to.
JsonFileInputOutput.saveObjectToTextFile(myObjectJson,
"/path/to/WalnutiQ/train/model/MARK_II/Digits.txt");

Why is my BufferedImage receiving a null value from ImageIO.read()

BufferedImage = ImageIO.read(getClass().getResourceAsStream("/Images/player.gif"));
First of all, yes I did add the image folder to my classpath.
For this I receive the error java.lang.IllegalArgumentException: input == null!
I don't understand why the above code doesn't work. From everything I read, I don't see why it wouldn't. I've been told I should be using FileInputStream instead of GetResourceAsStream, but, as I just said, I don't see why. I've read documentation on the methods and various guides and this seems like it would work.
Edit: Okay, trying to clear some things up with regards to what I have in the classpath.
This is a project created in Eclipse. Everything is in the project folder DreamGame, including the "Images" folder. DreamGame is, of course, in the classpath. I know this works because I'm reading a text file in /Images with info on the gif earlier on in the code.
So I have: /DreamGame/Images/player.gif
Edit 2: The line that's currently in the original post is all that's being passed; no /DreamGame/Images/player.gif, just /Images/player.gif. This is from a method in the class ImagesLoader which is called when an object from PlayerSprite is created. The main class is DreamGame. I'm running the code right from Eclipse using the Run option with no special parameters
Trying to figure out how to find which class loader is loading the class. Sorry, compared to most people I'm pretty new at this.
Okay, this is what getClassLoader() gets me: sun.misc.Launcher$AppClassLoader#4ba778
getClass().getResource(getClass().getName() + ".class") returns /home/gixugif/Documents/projects/DreamGame/bin/ImagesLoader.class
The image file is being put in bin as well. To double check I deleted the file from bin, cleaned the project, and ran it. Still having the same problem, and the image file is back in bin

Basically, Class.getResourceAsStream doesn't do what you think it does.
It tries to get a resource relative to that class's classloader - so unless you have a classloader with your filesystem root directory as its root, that won't find the file you're after.
It sounds like you should quite possibly really have something like:
BufferedImage = ImageIO.read(getClass().getResourceAsStream("/Images/player.gif"))
(EDIT: The original code shown was different, and had a full file system path.)
and you make sure that the images are copied into an appropriate place for the classloader of the current class to pick up the Images directory. When you package it into a jar file, you'd want the Images directory in there too.
EDIT: This bit may be the problem:
First of all, yes I did add the image folder to my classpath.
The images folder shouldn't be in the classpath - the parent of the Images folder should be, so that then when the classloader looks for an Images directory, it will find it under its root.

If you use resourceAsStream "/" referes to the root of the classpath entry, not to the root of the file system. looking at the path you are using this might be the reason.
If you load something from some home path you probably should use a FileInputStream. getResourceAsStream is for stuff that you deploy with your app.